"In the future, the global need for pain medicine will increase rapidly. In developed and developing countries, the world’s population is aging, resulting in an increase of the prevalence of chronic, painful conditions and cancer. By 2025, there will be 1.2 billion people over the age of 60, which is double the current estimate of 600 million.14 Future demand for such care is also expected to rise due to the dramatically expanding prevalence of HIV/AIDS in several parts of the world. Tragically, the greatest need for pain relief is increasingly concentrated in developing countries, where access to morphine and other opioid analgesics is inadequate or non-existent. For example, WHO estimates that the burden of cancer will increasingly shift from industrialized countries to developing states, so that by the year 2020, 70 percent of the estimated 20 million new cancer cases will occur in developing states.15"

Source

Taylor, Allyn L. "Addressing the Global Tragedy of Needless Pain: Rethinking the United Nations Single Convention on Narcotic Drugs," Journal of Law, Medicine & Ethics (Washington, DC: Georgetown University Law Center, January 2008 ) Vol. 35, No. 556, p. 558.
http://papers.ssrn.com/sol3/D…